Article
Undifferentiated SSc, clinical manifestations and disease progression of 282 patients into definite SSc subsets – data of the German Network for Systemic Scleroderma
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Published: | August 29, 2016 |
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Background: Systemic sclerosis (SSc) is a heterogeneous multisystem connective tissue disease, usually subdivided into the limited (lcSSc) and diffuse cutaneous SSc (dcSSc) by LeRoy and overlap syndromes. However, some patients present with symptoms suggestive of but not conclusive for a diagnosis of definite SSc. These patients have been referred to as very early or undifferentiated SSc subset (uSSc). It is defined as RP and at least one concomitant feature of SSc and/or detectable SSc-specific autoantibodies in SSc patients without fulfilling neither LeRoy nor ACR/EULAR SSc diagnosis criteria.
Methods: Up to date, more than 3400 patients have been registered within the German network for systemic scleroderma. All available follow-up visits of patients suffering from uSSc at initial patient registration were analysed to determine whether clinical features change over time and patients develop definite SSc.
Results: Among 3473 registered patients, 8.1% (282/3473) were diagnosed with uSSc at time of inclusion (mean age 59.9±1.5 years). A meaningful difference was detected as lcSSc patients were approximately 5 years and dcSSc 10 years younger than uSSc patients at time of diagnosis. Antinuclear antibodies (ANA) were positive in 77.7% (40.2% anti-centromer (ACA), 12.8% anti-topoisomerase (ATA) and 47% other SSc-specific antibodies).
34.0% of uSSc patients suffered from sicca symptoms, followed by 31.2% showing gastrointestinal, 30.5% musculoskeletal involvement, 14.5% lung fibrosis, 6.0% heart involvement and 5.0% pulmonary arterial hypertension.
Musculoskeletal and heart involvement were found equally in patients with uSSc and lcSSc, but significantly more often in patients with dcSSc. Lung fibrosis, pulmonary arterial hypertension and gastrointestinal involvement occurred significantly less often in patients with uSSc compared to lcSSc and dcSSc. After a mean follow-up time of nearly 4 years, a progression into lcSSc was observed in 16.3%, 4.6% converted into dcSSc and 3.2% were classified as overlap syndromes, while the majority of the patients remained within the subset uSSc (76.6%).
Conclusion: Patients with uSSc have been significantly older than other subsets at time of diagnosis (i.e. 5-10 years). During follow-up progression into a limited, diffuse or SSc overlap syndrome subset was observed in every fourth uSSc patient, however, the majority did not develop definite SSc.